High-frequency welding apparatus



June I, 1954 D. P. WORDEN ET AL HIGH-FREQUENCY WELDING APPARATUS FiledJune 29 1951 5 Shets-Sheet l ATTo/aA/E Y5 June 1, 1954 D. P. WORDEN ETAL HIGH-FREQUENCY WELDING APPARATUS 5 Sheets-Shget 2 Filed June 29, 1951/N VENTOEZS 00/1440 P l I/oEae/y Dad/X624 Jyz.

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HIGH-FREQUENCY WELDING APPARATUS Filed June 29 1951 5 Sheets-Sheet 5 y./N VENTOES Dom/94a flngmw .1656? M/ZL'QON/XCZL I Maw; f/jdgf ATTORNEYSJune 1, 1954 D. P. WORDEN ETAL HIGH-FREQUENCY WELDING APPARATUS 5Sheets-Sheet 4 Filed June 29 1951 1N VEN TOBS Dozvaza A h/ax? June 1,1954 D. P. WORDEN ET AL 2,680,180 HIGH-FREQUENCY WELDING APPARATUS FiledJune 29, 1951 5 Sheets-Sheet 5 Arr-0.42MB Y5 which is Patented June 1,1954 UNITED STATES PATENT OFFICE 2,680,180 HIGH-FREQUENCY WELDINGAPPARATUS Donald P.

Victor H. Payne, General Motors corporation of Worden, Joseph M.McDonnell, and

Rochester, N. Y., assignors to Corporation, Delaware Detroit, Mich., a

Application June 29, 1951, Serial No. 234,184

Claims.

This invention relates to an electrical welding apparatus and its objectis to provide such an being the Welder 3 together form of Fig. 1.

nd View in the direction of arrow a sectional view on of thebrushprovided by a cabinet or base which rests upon threaded engagementwith a screw i"! which exsupported above the table by a thrust bearingl9. Screw I! is attached to a worm gear 29 meshing with a worm attachedto a shaft 22 having a square end 23 to which a removable crank is to beattached. There are two other rods l3 one of which is shown in Fig. 3,which are associated with parts identical with parts I 4 to Therefore,by turning the shaft 22,-the four rods I 3 can be raised or lowered, toraise or lower a frame 25 which supports certain parts of the weldingapparatus.

To this end the four rods l3 are attached to the corners of a frame 25(Figs. 2 and 3) which supports at its left end a member 26 whichsupinsulated from frame 25 by insulators 21 and 28, while screws 29,which attach member 26 to frame 25, are insulated from said member, asshown in Fig. 7. At its right end, frame 25 supports a member 3!] whichis electrically insulated from frame 25 by member 3| and which carriescertain bearings and other mechanism later described.

The member 26 supports tapered roller bearings 33 a tubular copper shaft40 journaled in these bearings. Shaft 40 is located axially by thebearing 33a which engages a shoulrace of a ball bearing 5| supported bythe member 35, said race being confined against a shoulder 52 of shaft50 by lock washer 53 and a nut 54 threaded on shaft 50.

The flange 49 of shaft 50 is connected with an inner copper drum 55attached to a flange 56 (Fig. 2) of a copper shaft 51 which is supportedby and is located within the tubular shaft 49 in spaced concentricrelation thereto, the shafts 40 and 51 being separated by anon-conducting ring 58. The shafts 40 and 51 support, respectively,copper electrodes 60 and GI attached thereto by screws 62 and 63,respectively, threaded in the hard metal inserts 64 and 65,respectively.

The electrodes 60 and 6| are separated by an air gap and shaped toprovid a peripheral groove 65 which receives the tubing T which has beenformed by shaping a strip of steel into a cylinder with a buttseamextending longitudinally of the tubing and this apparatus is designed toweld this seam. The tubing T is urged against the electrodes by a roll"it supported below the tubing as shown in Figs. 1 and 2, journaled in alever ll pivotally supported at E2 by a standard :3 extending upwardlyfrom the base i l. The roll is urged upwardly against the tubing withsubstantially constant force exerted by air pressure within a bellowscontained in a housing '25 which is supported by the base it. supportingor back-up roll it and the mechanism for causing it to exert asubstantially constant pressure on the tubing to be welded disclosed inthe patent to R. I. Hahn et al. No. 2,492,572, granted December 27,1949. The details of this mechanism constitute no part of the presentinvention.

Electrode rolls cc and (ii are initially larger in diameter than shown.For example, the initial size of the rolls shown in Fig. 2 may be thatrepresented by the dot-dash circle 68 in Fig. 1. To accommodateelectrodes of such diameter, it is necessary to elevate the frame (Figs.2 and 3) so that the axis of the electrodes and supported shafts will beinitially that represented by the dot 51 (Fig. l). The supporting member26 is designed to support apparatus for trimming and grooving theelectrodes. This apparatus is not shown because it forms no part of thisinvention,

but may be of the same construction as that T shown in the patent toNichols 2,2933%, granted August 25, 1942. This operation of trimming andgrooving the electrodes is necessary because of the fact that during thecontinued use of the machine, the tube receiving groove becomes Lroughened and worn out of true due to the intense heat of the electriccurrent and must be trued or resurfaced in order for the device tocontinue to operate properly.

Rotation of the electrodes during the welding operation is effected bythe traction between the longitudinally moving tubing and theelectrodes, said traction being effective due to the pressure exerted bythe back-up roll Ell. For trimming and grooving the electrodes when thewelder is not in use, the electrodes are rotated by means of an electricmotor (Fig. l) which drives a grooved pulley 85 connected by a belt 82with a pulley 83, which, as shown in Fig. 3, is provided with a bearingbushing 84 journaled on a disc 85 supported by shaft 5%. Pulley 83carries pins 85 (Fig. i) which pivotally supports pawls a: urged bysprings 33 toward a ratchet B9 connected with shaft 5@ in any suitableway. Ratchet 8% is retained in the position shown by washers 93 and 9!(Fig. 3) which are engaged by a flange formed on a plug 92 screwed intothe shaft 50.

As previously stated, the inner drum of the transformer secondary is suplied with water for cooling purposes and to this end the plug 9?. hasformed therein a water inlet duct 93 which connects with a water inletpassage 34 extending to a source of supply. The passage or duct 93 alsocommunicates with a pipe 35 which extends to a point near the left endof shaft 51 so that the incoming water is discharged against theelectrode 51. The discharged water flows to the right through the shaft5? and partly fills the drum 55, the excess flowing out through the ductes, formed in the plug 92 and a discharge passage 9'! formed in acoupling member Gil, secured to the plug 92 and in which the watersupply passage 94 is also formed. The drum 55 and the shaft 5c retain asubstantial quantity of water at all times The details of the All duringthe operation of the apparatus. This water conducts away heat withoutbeing brought up to the boiling point since cold water is flowing in tomaintain the level of water at about the axis of the drum.

The annular space 99 between the drums 45 and 55 receives the primarytransformer winding I58 which is wound around a relatively thin core HMas shown in Figs. 2 and 3. This core is made by winding a thin ribbon ofsilicon steel into a hollow cylinder. As already stated, this steel isof a type known to the trade as Hipersil Type C. The core IGI hasrelatively low reluctance to change in flux density and is capable ofhigh saturation, so that it is responsive to high frequency current onthe order of 960 cycles. The primary winding Hill of insulated wire isencircled by bands I52 which are fixed to the inside wall of the drum 55by screws Hi3 and which space said primary winding from the drum 45.

The lead wires H35 and I (Fig. 3) of the coil I06 are connected withcopper rings Hi6 and i0! which are secured by screws N38 to anon-conducting annular plate or ring 1% of suitable insulating materialattached to the annular member 41. Each of the rings is engaged by twobrushes l l i movable in brush holders I 12, pairs of which are attachedto each of copper plates H4 and H5 and leaf springs H3 urge the brushestoward the rings. The brush holders H2 are attached to the plates H4 andH5 by bolts H5cL or other means and the plates are secured in anysuitable way to a supporting bracket H6 (Fig. 3), supported by anon-conducting plate ill, to which it is secured in any suitable way.The plate is secured by bolts or other suitable means to a supportingbracket H8 which is at tached by screws He to the bracket 29. Thebrushes are held in contact with the rings I03 and it! by leaf springsH3, each of which is secured at one end to a pin H311 carried by thebrush holder and at the other end engages the brush as shown in Fig. 6.

The brushes are connected by pig-tails are to pairs of conducting posts12! and I22. attached, respectively, to the plates H4 and H5. One ofeach of the pairs of posts I21 and 522 is connected respectively withwires H3 and I24 which are connected with a source of alternatingcurrent, of such high frequency as desired, 960 cycles for example.

This apparatus is particularly adapted for use in practising the methodof high frequency welding disclosed in the copending application ofDonald P. Worden et al., Serial No. 218,572, filed March 31, 1951.

The advantages of the transformer which constitutes a part of thewelding apparatus disclosed are several. The Hipersil steel ribbon,which is only approximately .005" thick and independently insulated, hasthe effect of reducing eddy current loss. A further advantage resides inthe fact that Hipersil will carry in the same volume of material 35%more magnetic flux density with approximately 25% less total core loss,as compared to standard grades of transformer steel.

Further beneficial results are brought about by the construction of theprimary winding. The winding comprises a number of groups having aminimum number of turns per group, connected in series. For example,there may be 21 groups of 3 turns each and 11 groups of 2 turns each, anarrangement which gives excellent results. By limiting the number ofturns in each group to a practical minimum, the reactance revoltage isapproximately 116, while the total loss, core loss plus other losses isapproximately 650 watts.

Another beneficial result arises from the fact that a relatively largeand unobstructed drain is provided for the cooling water so that thereis a cons1derable flow of cooling water during opthe device increasingthe cooling eifect.

that the welding apparaformer steel, but such apparatus would be lessefficient than when a core of Hipersil steel is employed, as has beenpreviously indicated.

While the embodiment of the present invention as herein disclosedconstitutes a preferred form, it is to be understood that other formsmight be adopted.

What is claimed is as follows:

1. An electric welding apparatus comprising a pair of electrodesconnected with a source of A. C. current of relatively high frequencyand separated by an air gap, said apparatus having a transformerincluding a primary winding comprising a plurality of loops of insulatedwire, each of which has a plurality of turns, surrounding a cylindricalcore formed of Hipersil steel and a secondary comprising a pair ofconcentric, spaced drums between which the primary winding ispositioned, one of said drums being connected to each of saidelectrodes, and means for holding the article to be welded against saidelectrodes adjacent the air gap with a substantially constant pressure.

2. An electric welding apparatus comprising a pair of electrodesconnected with a source of A. C. current of relatively high frequencyand separated by an air gap, said apparatus having a transformerincluding a primary winding surrounding a steel core and being cut awayadjacent the air gap to form a groove adapted to receive a tube having abutt seam to be welded, means for holding the tube against theelectrodes with the seam adjacent the air gap with a substantiallyconstant pressure, a transformer having a secondary formed 6, ofitwo'spaced concentric rotatable drums; con' centric shafts spaced andinsulated from each other, one of which is connected to each of saiddrums, and each of which is rotatably supported, and means forconnecting one of said electrode discs to each of said shafts. I

4. An electric welding apparatus comprising a pair of rotatableelectrode discs connected with a source of A. C. current of relativelyhigh frequency and separated by an air gap, said discs air gap with asubstantlally drum to the electrode disc secured to said shaft, and awater supply conduit extending into said bore and discharging coolingwater against said last named electrode disc.

6. An electric welding apparatus comprising a pair of rotatableelectrode discs connected with a source of A. C. current of relativelyhigh frequency and separated by an air gap, said discs being cut awayadjacent the air gap to form a groove adapted to receive a tube having abutt seam to be welded, means for holding the tube against theelectrodes with the seam adjacent the air gap with a substantiallyconstant pressure, a transformer having a secondary formed of two spacedconcentric rotatable drums, one of which is connected to each of saidelectrodes and each core formed of a relatively thin ribbon of Hipersilsteel wound in the'form of a cylinder and positioned in the annularspace between said concentric drums.

7. An electric welding apparatus comprising a pair of rotatableelectrode discs connected with a source of A. C. current of relativelyhigh frequency and separated by an air gap, said discs being cut awayadjacent the air gap to form a groove adapted to receive a tube having abutt means for holding the tube against the electrodes with the seamadjacent of two spaced concentric rotatabledruma'one of which isconnected to each of said electrodes and a primary winding positioned inthe annular space between said concentric drums, said winding comprisinga plurality of groups of connected wire loops each having a relativelysmall number of turns which are wound around a steel core formed of athin ribbon of Hipersil steel wound in the form of a cylinder.

8. An electric welding apparatus comprising a pair of electrodesconnected with a source of A. C. current having a frequency of at leastapproximately 960 cycles and separated by an air gap and a transformerhaving a secondary comprising a pair of concentric drums, one of whichis connected to each of said electrodes and sepa rated from each otherto form an annular space between said drums and a primary windingsurrounding a core formed of a relatively thin ribbon of Hipersil steelwound in the form of a cylinder and positioned in the annular spacebetween said concentric drums.

9. An electric welding apparatus comprising a pair of electrodesconnected with a source of A. C. current of relatively high frequencyand separated by an air gap and a transformer having a secondarycomprising a pair of concentric drums, one of which is connected to eachof said electrodes and separated from each other to form an annularspace between said drums and a primary winding positioned in the annularspace between said concentric drums, said winding comprising a pluralityof groups of connected wire loops each having a relatively small numberof turns which are wound around a steel core formed of a thin ribbon ofHipersil steel wound in the form of a cylinder, and said loops of wirehaving different numbers of turns therein.

10. An electric welding apparatus comprising a pair of electrodesconnected with a source of A. C.

current of relatively high frequency and separated by an air gap, and atransformer having a secondary comprising a pair of concentric drums,one of which is connected to each of said electrodes and separated fromeach other to form an annular space between said drums, and a pri-; marywinding positioned in the annular space between said concentric drums,said winding comprising a group of connected wire loops, each loophaving a relatively small number of turns and a second group of wireloops each of which has a lesser number of turns than the loops of thefirst group, all of said wire loops being wound around a cylindricallyshaped core of Hipersil steel.

11. An electric welding apparatus comprising a pair of electrodesconnected with a source of A. C. current of relatively high frequencyand separated by an air gap, and a transformer having a secondarycomprising a one of which is connected to each of said electrodes andseparated from each other to form an annular space between said drums,and a primary winding positioned in the annular space between saidconcentric drums, said winding comprising a group of connected wireloops each loop having three turns, and a second group having adifferent number of wire loops each of which has only two turns, all ofsaid wire loops being wound around a cylindrically shaped core ofHipersil steel.

12. An electric welding apparatus comprising a pair of rotatableelectrode discs connected with a source of A. C. current of relativelyhigh frequency, and separated by an air gap, a transformer comprising aprimary winding surrounding a steel core and a secondary comprising apair of concentric spaced drums between which pair of concentric drumsthe primary winding is positioned, a pair of spaced concentric shaftsextending from said drums, each of which supports one of said electrodediscs and means for adjusting the position of said discs on thesuporting shafts, whereby the width of the air gap can be varied asdesired.

13. An electric welding apparatus comprising .a pair of rotatableelectrode discs separated by an air gap, a transformer comprising aprimary winding surrounding a steel core and a secondary comprising apair of rotatable concentric spaced drums between which the primarywinding is positioned, a pair of concentric shafts extending from saiddrums and supporting said electrode discs, a plurality of separatedmetal plates rotatable with and supported on one of said drums, each ofwhich is connected with one end of the primary winding, brushes engagingsaid plates, a fixed support for said brushes, means for connecting saidbrushes with a source of relatively high frequency A. C. current andmeans for rotating the transformer and electrode discs.

l. An electric welding apparatus comprising a pair of rotatableelectrode discs separated by an air gap, a transformer comprising aprimary winding surrounding a steel core and a secondary comprising apair of rotatable concentric spaced drums between which the primarywinding is positioned, a plurality of concentric shafts, one of whichextends from each of said drums at one end thereof, a shaft extendingfrom and supported by the inner drum at its opposite end, supportingstandards at opposite ends of said transformer, one of said standardshaving a bearing in which the last named shaft is rotatably supported, abearing mounted in the other of said standards for rotatably supportingthe outer of said concentric shafts and means for rotating thetransformer and electrode discs.

15. ,An electric welding apparatus comprising a pair of rotatableelectrode discs separated by an air gap, a transformer comprising aprimary winding surrounding a steel core and a secondary comp-rising apair of rotatable concentric spaced drums between which the primarywinding is positioned, a plurality of shafts one of which extends fromeach end of the inner drum, a hollow shaft extending from one end of theouter drum .and surrounding one of said first mentioned shafts,supporting standards at opposite ends of the transformer, one of saidstandards having a bearing in which said last-named shaft is rotatablysupported, a bearing mounted in the other of said standards in which oneof the shafts extending from the inner drum is rotatably supported, andmeans for rotating the transformer and electrode disks.

References Cited in the file of this patent UNITED STATES PATENTS OTHERREFERENCES Book, Magnetic Circuits and Transformers by E. E. Staff M. I.T., 1943, page'289v (Division 48.)

